Death Valley National Park - Climate

Climate

Death Valley is the hottest and driest place in North America because of its lack of surface water and its low relief. It is so frequently the hottest spot in the United States that many tabulations of the highest daily temperatures in the country omit Death Valley as a matter of course. On July 10, 1913, a record 134 °F (56.7 °C) was measured at the Weather Bureau's observation station at Greenland Ranch (now the site for the Furnace Creek Inn), the highest temperature ever recorded in the world. Daily summer temperatures of 120 °F (49 °C) or greater are common, as well as below freezing nightly temperatures in the winter. July is the hottest month, with an average high of 115 °F (46 °C) and an average low of 88 °F (31 °C). December is the coldest month, with an average high of 65 °F (18 °C) and an average low of 39 °F (4 °C). The record low is 15 °F (−9.4 °C).

Several of the larger Death Valley springs derive their water from a regional aquifer, which extends as far east as southern Nevada and Utah. Much of the water in this aquifer has been there for many thousands of years, since the Pleistocene ice ages, when the climate was cooler and wetter. Today's drier climate does not provide enough precipitation to recharge the aquifer at the rate at which water is being withdrawn.

The highest range within the park is the Panamint Range with Telescope Peak being its highest point at 11,049 feet (3,368 m). The Death Valley region is a transitional zone in the northernmost part of the Mojave Desert and consists of five mountain ranges removed from the Pacific Ocean. Three of these are significant barriers: the Sierra Nevada, the Argus Range, and the Panamint Range. Air masses tend to lose moisture as they are forced up over mountain ranges, in what climatologists call a rainshadow effect.

The exaggerated rainshadow effect for the Death Valley area makes it North America's driest spot, receiving about 1.5 inches (38 mm) of rainfall annually at Badwater (some years fail to register any measurable rainfall). Annual average precipitation varies from 1.92 inches (49 mm) overall below sea level to over 15 inches (380 mm) in the higher mountains that surround the valley. When rain does arrive it often does so in intense storms that cause flash floods which remodel the landscape and sometimes create very shallow ephemeral lakes.

The hot, dry climate makes it difficult for soil to form. Mass wasting, the down-slope movement of loose rock, is therefore the dominant erosive force in mountainous area, resulting in "skeletonized" ranges (mountains with very little soil on them). Sand dunes in the park, while famous, are not nearly as numerous as their fame or the dryness of the area may suggest. One of the main dune fields is near Stovepipe Wells in the north-central part of the valley and is primarily made of quartz sand. Another dune field is just 10 miles (16 km) to the north but is instead mostly composed of travertine sand. Yet another dune field is near the seldom-visited Ibex Hill in the southernmost part of the park, just south of the Saratoga Springs marshland. Prevailing winds in the winter come from the north, and prevailing winds in the summer come from the south. Thus the overall position of the dune fields remains more or less fixed.

There are rare exceptions to the dry nature of the area. In 2005, an unusually wet winter created a 'lake' in the Badwater Basin and led to the greatest wildflower season in the park's history.